1. Field of the Invention
The present invention relates to a ground-working machine and, more particularly, to an agricultural machine for pruning field crops, and low bushes on a commercial scale.
2. Description of the Prior Art
It is well known that Blueberries and like perennial crops may be treated periodically by pruning the bushes and thereby encourage future regrowth and improve fruit output. Conventionally, pruning of Blueberry bushes on a commercial scale is accomplished by burning off of the plants with oil fired burners. While this effectively prunes the plants without serious damage to their root systems, it also destroys much of the organic material in the soil, and is fairly energy intensive. This is also not an environment-friendly method of pruning the bushes.
Flail type cutting and shredding machines are well known in the agricultural industry but have not been popularly used to prune bushes of Blueberries and like perennial crops. Flail type cutting and shredding machines generally comprise a plurality of hangers fixed around the outside perimeter of a shaft. A plurality of small blades are hooked onto the hangers by means of a bolt positioned through a pair of the hangers. The shaft is rotated by a pulley and belt assembly or chain and sprocket assembly and carried over the ground on a roller or on skid shoes, and the blades slash into the bushes which are to be cut. The pulley and belt or the chain and sprocket assemblies may be driven by an hydraulic motor attached to the machine or driven by the power take-off system of a towing vehicle by means of a driving shaft and universal joints. Examples are described in U.S. Pat. No. 3,599,412, entitled FLAIL SHREDDER and issued to Lefeuvre et al. on Aug. 17, 1971, U.S. Pat. No. 5,485,718, entitled FLAIL CUTTER AND METHOD OF PROVIDING A FLAIL CUTTER FOR A BRUSH CUTTING MACHINE and issued to Dallman on Jan. 23, 1996, and U.S. Pat. Nos. 5,570,571 and 5,733,385, both entitled BLADE FOR A FLAIL TYPE BRUSH CUTTING MACHINE and issued to Dallman on Nov. 5, 1996 and Mar. 31, 1998 respectively. Dallman improves the flail type cutting machine with a flexible connection of the blades to the shaft. A bolt positioned through a pair of hangers fixed on the shaft, holds a ring which in turn holds a pair of blades. The attaching hole in the blades for attaching the blade to the ring is a elliptical shape to provide more room for the blade to slide on the ring, which allows the blade to swing back and forth more readily as it slashes through the bush to be pruned. In order to achieve larger cutting areas, a number of separate flail type cutting machines can be combined in a single apparatus, as back and front additions to a tractor. One example is described in U.S. Pat. No. 4,631,910, entitled MOWER, ESPECIALLY FOR GRASS AT AIRPORTS and issued to Doyen et al. on Dec. 30, 1986. Doyen et al. describe an arrangement for combining a number of separate flail type machines in which a first machine is attached closest to a tractor""s width on the front of the tractor and additional machines are attached to the back of the tractor in pairs, offset to either side of the front machine so that the pairs of machines attached to the back are staggered, and in which at least one additional hydraulic motor independent of the tractor motor is attached to drive the back machines.
Those prior art machines have not been successfully used to prune bushes of the like perennial crops. Therefore, there is an existing need for a pruning apparatus, particularly for cutting and shredding lower bushes on the ground surface, such as Blueberries on a commercial scale.
It is one object of the present invention to provide a pruning apparatus adapted to prune low bushes on the ground surface.
It is another object of the present invention to provide a pruning apparatus adapted to prune low bushes, particularly Blueberries on a commercial scale.
It is yet another object of the present invention to provide a connection arrangement for conveniently combining a selected number of pruning units into a pruning machine having a selected pruning width.
It is a further object of the present invention to provide a relatively uniform pruning of low bushes on an uneven ground surface.
In accordance with one aspect of the present invention, a pruning apparatus is provided. The pruning apparatus comprises a plurality of ground work units, each including a plurality of tool members operatively connected to a drive shaft rotatably supported by a housing and rotated by a drive means for effectively pruning a sub-area of a ground surface when being advanced; a wheeled main frame adapted to be towed behind a propelling vehicle, the main frame selectively connecting a number of the ground work units staggered in front and rear rows to provide a selected width of a pruning area including the pruning sub-areas of the individual ground work units; and a connecting means for connecting the respective ground work units to the main frame, with the connecting means each ground work unit being pivotable with respect to the main frame, about a forwardly directing and substantially horizontal axis within a limited range, and pivotable about a vertical axis, and also being slidable to a selected transverse position relative to the main frame, whereby the pruning apparatus generally conforms to an uneven contour of the ground surface and effects continuous and relatively consistent pruning along the entire selected width of the pruning area.
It is preferable that the connecting means includes a plurality of connecting bars, each having a predetermined length and being pivotally connected at a front end thereof to the main frame and slidably connected at a rear end to one of the ground work units.
The connecting bar in accordance with one embodiment of the present invention includes an aperture at the front end thereof for receiving a pivoting pin which vertically extends through the aperture of the connecting bar and a hole in the main frame. At least either one of the aperture and the hole, is greater than the diameter of the pivoting pin in order to permit the connecting bar to be pivotable, not only about the pivoting pin but also about a longitudinal axis of the connecting bar within a limited range. At the rear end, the connecting bar has a sleeve secured thereto. The sleeve has a central axis perpendicular to the longitudinal axis of the connecting bar and slidably surrounds a sliding rod secured to the ground work unit. The sliding rod is parallel to the drive shaft of the ground work unit.
In this embodiment each ground work unit includes a housing having an open bottom and a drive shaft rotatably supported to the housing. Each of the tool members operatively connected to the drive shaft is in a general L-shape having an outer cutting section with cutting edges and an inner mounting section. An elongated aperture is provided in the inner mounting section, extending along a longitudinal axis of the inner mounting section. A plurality of pairs of axially spaced brackets are fixed to a peripheral surface of the drive shaft. A U-shaped connector extends loosely through the elongated aperture in the inner mounting section of a pair of the tool members that are secured to abut each other at the inner mounting sections in order to form a general T-shape. A pin pivotally connects two ends of the U-shaped connector to the axially spaced brackets. When the drive shaft is rotated and advanced, the tool members swing and slash into the bushes to achieve a pruning effect by both cutting and flailing actions. The elongated aperture in the inner mounting section of the tool member provides more room for the tool member to slide on the U-shaped connector and permits the tool member to swing back and forth more readily as it slashes through the bushes which are to be cut. Thus, the ground work unit is adapted to effectively prune both small and tender branches as well as the relatively thick stems of bushes.
A drive chain and sprocket assembly is preferably provided for rotating the drive shaft. The chain and sprocket assembly is operatively supported by the housing of the ground work unit. A sliding rod is also supported on the housing and preferably extends along the entire length of the ground work unit. Each of the ground work units is supported on the ground surface, for example, by a pair of skid shoes or a pair of elongated rollers which are adjustable relative to the housing so that the ground work unit is supported in a selected vertical position with respect to the ground surface in order to determine a pruning depth.
The embodiment of the present invention is provided with a lift system including an hydraulic cylinder, pivoting arms and lift chains to lift the respective ground work units with respect to the main frame so that the ground work units may be raised off the ground surface when it is requested, such as for transportation.
The respective ground work units according to this embodiment are driven by a power distribution system which includes a gear box with a clutch operatively connected to a power take-off system of the towing vehicle. A number of power drive shafts are used to transmit a rotation movement from the power take-off system of the vehicle to the drive chain and sprocket assembly of the respective ground work units. The drive shafts are connected to the drive chain and sprocket assemblies and the gear box by means of universal joints.
The present invention provides a convenient arrangement for combining a selected number of ground work units into a pruning apparatus having a desired pruning width. The sliding connection between the connecting bar and the sliding rod of the ground work unit enables the ground work unit to be selectively positioned in a transverse position in each row with respect to the main frame so that when the number of ground work units to be used is changed, for example, from 3 units to 2 units, the position of the ground work units can be easily adjusted to ensure the ground work units in front and rear rows are staggered properly, whereby the pruning areas effected by the respective ground work units overlap and form a continuous and relatively consistent pruning area having a desired width.
The connection between the connecting bar and the main frame permits pivotal movements around both a vertical axis and a substantially horizontal axis in a forward direction. This connection permits each ground work unit to be independently pivotable about a substantially horizontal axis to adapt to an uneven ground surface. A typical connector for such a purpose is a universal joint. Nevertheless, according to the present invention, this connection is achieved by a connecting pin vertically extending through apertures in the front end of the connecting bar and in the main frame. Conventionally, such a connecting pin provides a connection pivotable only about a vertical axis, but not about a substantially horizontal axis in the forward direction. In order to provide limited pivoting around a substantially horizontal axis in the forward direction for the ground work unit, relative to the main frame, the diameter of either one or both of the apertures in the connecting bar and in the frame is greater than the diameter of the connecting pin to such an extent as to permit the connecting bar to rotate at a slight angle around its longitudinal axis when the connecting bar is such connected to the main frame. It is noted that the pruning apparatus is generally used on agricultural lands which have a generally flat ground surface with slightly uneven areas such as embranchment areas or sections of lands adjacent to a roadside. The limited pivoting feature of a ground work unit is satisfactory to conform to the slightly uneven surface of these areas of lands. This connection structure is therefore simpler and as a result, manufacturing costs are reduced.